Sorry for the late reply.
You'll need to keep an eye on the stress and strain along the bend radius as it deflects, increasing the weight until it reaches failure or exceeds it's permissible limits. This is how kinks and wrinkles form.
Wall thickness and material strength will be the big players in this game. If you really want to slug it out, you can use work/energy methods but as you'll want to change factors as you go, I'd recommend using a good FEA package.